Fusarium spp. update March 2015

Earlier research has shown that the fungus Trichoderma harzianum strain INAT 11 can be used as an antagonist to control Fusarium pathogens in cereals. In the first year of the BIOCOMES project, unique DNA primers for Trichoderma harzianum strain INAT 11 are characterized by Graz University of Technology and the influence of environmental factors on growth were investigated.

Strain-specific detection

The purpose of developing primers is to be able to fulfill requirements for registration in the EU:

1. Identify the strain on a strain level
2. Distinguish it from other naturally occurring and/or commercially available Trichoderma harzianum strains
3. Detect its presence in treated soil, and thus to obtain information on persistence and environmental fate

However, DNA primers can help to detect the strain, but they cannot tell whether it is alive. So, the DNA primers can detect spores, but these primers do not tell whether the spores are dead or alive. In order to be sure that spores are alive, other additional studies are necessary.

Influence of environmental factors on the growth of Trichoderma harzianum strain INAT 11

After the characterization of a unique primer, the influence of the environmental factors temperature, water activity (a_w) and acidity (pH) on the growth of Trichoderma harzianum strain INAT 11 have been investigated by BIOGARD and the University of Padova. Lab experiments showed that temperature, a_w and pH were limiting factors for fungal growth, however in soil pH had no effect on the survival rate of this antagonist. Trichoderma harzianum lives very close to the roots where growth conditions are generally better (exudates can play a key-role). After these experiments, in vitro trials were carried out to measure the influence of several fungicides, herbicides and insecticides on mycelial growth of Trichoderma harzianum strain INAT 11. All the tested fungicides tested up to date were toxic to the strain at the dose of 1 ppm, while mycelial growth was not affected by one out of the two tested insecticides and by two out of the five tested herbicides.

Minimum dose

Defining the minimum effective dose of Trichoderma harzianum strain INAT 11 and its effect on root colonization by Fusarium spp. was the next step. These experiments just started because of a delay in the formulation development. Seed treatment and semi-field tests will be performed during 2015.

Formulation

Tests have been carried out to develop an effective commercial formulation of Trichoderma harzianum strain INAT 11 and to optimize shelf-life. Trichoderma harzianum can be produced by liquid or solid fermentation. The spores have to be mixed with adequate co-formulants in order to produce a proper formulation. For the formulation experiments the following features will be taken into account:

• Reasonable shelf-life
• Good adherence and distribution of the spores on the seed surface
• Long spore viability
• Easy to be distributed onto the seeds

The amount of formulated product required should be appropriate to be used with already available seed dressing machines (corn = 40 kg of seed/ha)

Read more about our activities on fusarium spp.